Continued...
Engines
The 2014 Pentagon report on Chinese military power observed, “China faces numerous challenges to achieving full operational capability, including developing high-performance jet engines.” The flight characteristics of the J-20 are limited by inadequate engines because of delays in the development of the Chinese WS-15 engine, which is supposed to have about 40,000 pounds of thrust and thrust vectoring. The prototypes of the J-20 seem to be equipped with Russian AL-31FN engines, which lack thrust vectoring or adequate power to achieve supercruise speed or high maneuverability.
To compensate for the WS-15 problems, China is procuring the Russian Su-35 fighter to get its 117S engines, the most advanced Russian fighter engines. The sale of Su-35s to China was long delayed by Russia’s concern about Chinese reverse engineering. The Russian engine, however, reportedly will not have enough thrust to give the J-20 supercruise capability, though it will improve aerodynamic performance and provide thrust vectoring.
Lockheed Martin says the F-35 has a limited supercruise capability (150 miles at Mach 1.2.) giving it an advantage over the current J-20. If the F-35 thrust is increased through engine improvements, this should increase its supercruise potential and give it an advantage even over a J-20 equipped with the Russian engines.
Sensors
The J-20’s sensor capabilities appear to be impressive. In addition to its active electronically scanned array (AESA) radar, the Chinese appear to have copied the stealthy electro-optical targeting system sensor housing from the F-35. The J-20 reportedly also has a 360-degree optical counterpart to the F-35s distributed aperture system. Just because it looks the same does not mean that it works the same. While the J-20’s AESA radar probably gives it enhanced detection against low RCS targets (compared to passive array or mechanically scanned radars), not all AESA radars have the same power and capabilities, including stealth, electronic protection, and electronic warfare capability. According to press reports, the F-35’s APG-81 radar operates “in LPI (low probability of intercept) and LPD (low probability of detection) modes that minimize the aircraft’s signature to comply with its low observable (LO) requirements. The radar is optimized for agility, very low noise, high efficiency, and fully supports the LO nature of the aircraft.” Since the J-20 radar is an early Chinese AESA, it is unlikely to be in the same class as the radar on the F-35. Moreover, it is unlikely China can match the “flying super computer” capabilities of the F-35, including sensor integration and networking to improve pilot situational awareness.
Assessment
In 2015, then-chief of the F-35 joint program office Lieutenant General Christopher Bogdan, U.S. Air Force, commented, “I’d put this airplane up against any airplane in the world today, tomorrow and for the next 20 or 30 years, and we will come out ahead.” The Air Force says the F-35 achieved 110 “kills” against “adversary aircraft” in Exercise Northern Lightning and achieved a 20-to-1 kill ratio in the early 2017 Red Flag exercise. Marine F-35Bs reportedly suppressed SAM sites without being targeted.
Overall, the J-20 is likely to be a serious threat to U.S. aircraft, ships, and bases for the foreseeable future. While the F-35 has better stealth and sensor capability and the J-20 may not be a matchup one-on-one, the Chinese may be able to put more of them in the sky. In 2017, General Herbert Carlisle, Commander Air Combat Command, stated that in the South China Sea the threat may be “10 squadrons of J-20s, plus Su-35s…and Su-30s and J-10s and J-11s.” So, while not as good as the F-35, the J-20 does not have to be as stealthy or have sensor parity to have an impact on the Far East military balance.
